Refastenable mechanical fastening systems are well known in the art. Typically, such fastening systems involve two major components, a prong which is joined to a substrate and engages with a complementary second component, the receiving surface. A projection of the prong of the fastening system penetrates the receiving surface and either engages or intercepts strands or fibers of the receiving surface. The resulting mechanical interference and physical obstruction prevent removal of the fastening system from the receiving surface until the separation forces exceed either the peel or shear strength of the fastening system.
Presently, refastenable mechanical fastening systems are made by at least two general methods. One method requires a plurality of filaments, each of which may be formed into two prongs. Examples of fastening systems produced by this method are shown in U.S. Pat. No. 2,717,437, issued Sep. 13, 1955 to de Mesteral and U.S. Pat. No. 3,943,981, issued Mar. 16, 1976 to De Brabandar which teach a raised pile of loops. Related teachings are shown in U.S. Pat. No. 4,216,257, issued Aug. 5, 1980 to Schams et al., U.S. Pat. No. 4,454,183, issued Jun. 12, 1984 to Wollman and U.S. Pat. No. 4,463,486, issued Aug. 7, 1984 to Matsuda. These references teach heating the ends of polymeric monofilaments. Other related teachings of fastening systems produced by the first method are disclosed in U.S. Pat. No. 4,307,493, issued Dec. 29, 1981 to Ochiai and U.S. Pat. No. 4,330,907, issued May 25, 1982 to Ochiai.
The second general method commonly utilized to manufacture mechanical fastening systems is to mold or extrude the systems as illustrated in U.S. Pat. No. 3,147,528, issued Sep. 8, 1964 to Erb and U.S. Pat. No. 3,594,863, issued Jul. 27, 1971 to Erb. Continuous injection molding is taught in U.S. Pat. No. 3,594,865, issued Jul. 27, 1971 to Erb.
Various prong structures are illustrated in the prior art. For example, the references discussed above teach fastening systems having stems of generally constant cross section. U.S. Pat. No. 3,708,833, issued Jan. 9, 1973 to Ribich et al. discloses a prong which is somewhat tapered from the proximal end to the distal end and perpendicularly projects from the substrate.
European Patent Application No. 0,276,970, published Aug. 3, 1988, by the Procter & Gamble Company in the name of Scripps discloses a fastening device having a constant cross section stem oriented at an angle between about 30.degree. and about 90.degree. relative to the base.
The fastening systems of the prior art are relatively expensive to produce, and the processes of the prior art are relatively slow. Additionally, the fastening systems of the prior art are irritating and abrasive to human skin and are, therefore, not well suited for applications which cause them to be in close proximity to human skin. There is, therefore, a need for a fast and inexpensive method of producing mechanical fastening systems. There is also a need for mechanical fastening systems which are non-irritating and non-abrasive to human skin.
Some of these needs have been addressed in U.S. patent application Ser. No. 07/668,817 filed Mar. 7, 1991 in the name of Dennis A. Thomas, entitled "Refastenable Mechanical Fastening Means and Process of Manufacture Therefor", which discloses a method of manufacturing a refastenable mechanical fastening system rapidly and inexpensively by a method similar to gravure printing.
However, the present invention discloses a faster and less expensive method of producing a mechanical fastening system than the prior art. The method of the present invention also produces a fastening system having an array of prongs that is more dense, and therefore is less abrasive and less irritating, than the fastening systems of the prior art.